What Does Stormwater Mean?
Stormwater is the rainfall that falls onto paved or other impermeable surfaces – roofs, parking lots, streets and driveways – and continues to flow onto and across the ground. If the stormwater is absorbed into the ground, it becomes groundwater. Some rain events, however -- like a 100-year storm -- produce rain in such concentrations that the ground can't absorb it. Then, stormwater becomes a problem. The problems cause by stormwater create the need to repair damaged pipes, replace over-laden places, or install new sewer pipes in effected areas.
Also referred to as runoff or stormwater runoff.
Trenchlesspedia Explains Stormwater
What happens when the ground is saturated and stormwater -- sometimes called storm runoff or just runoff -- isn't absorbed?
One of the first, most noticeable hazards associated with stormwater is flooding.
Runoff can pick up dirt, nitrogen, phosphorous, acids, alkilis,
oils, greases and other materials that accumulate on roofs and ground surfaces. It can also pass through yards that may contain fertilizers or pesticides. Stormwater, laden with these chemicals and other materials, can pass into a municipality's sanitary sewers, storm sewers and into water treatment plants, creating a public nuisance or public hazard if the treatment plant is not designed for the quantity of runoff and the toxins it may carry.